Concerns of a Climate Scientist

What concerns me most about climate change now is the contrast between the apathy of the public and the troubling facts that we climate scientists have established. Most people are poorly informed about what our science has discovered, and most political leaders have done little or nothing to cope with the threat of climate change. In the United States, we also have the sad spectacle that almost the entire national leadership of the Republican party simply does not accept the most basic findings of mainstream climate science. In the 2012 US Presidential election, the topic of climate change was essentially ignored by both sides. Problems cannot be solved by pretending they do not exist, and future generations will not judge us kindly unless we accept the science and act quickly.

The mainstream media bear part of the blame for inadequately covering climate change. This topic should be recognized by everyone as a threat deserving high priority. The existential threat of climate change affects national security, economic prosperity, and the health and safety of people throughout the world. It should not be marginalized as a niche issue of interest only to a few people whom we label as “environmentalists.” Journalists should never make the mistake of framing the issue as a controversy – is man-made climate change real and serious or not – in which both sides deserve equal time. In addition, all of us need to realize that an effective and well-funded professional disinformation campaign has succeeded in confusing many people about the seriousness of the threat and the urgency of acting to limit climate change.

The plain fact is that what mankind decides to do in the coming years and decades will largely determine the climate that our children and grandchildren will inherit. To meet the very real threat of climate change caused by human activities, the political process must listen to the science and then must act. Humanity needs to decide collectively how much man-made climate change is acceptable. Science cannot specify what level of climate change is “dangerous.” That is a question involving risk tolerance, values, priorities and other subjective concerns. Governments will decide, by their actions or inactions.

We already have a tentative decision. Many governments have now adopted the aspirational goal of limiting global warming to 2 degrees Celsius (or 3.6 degrees Fahrenheit) above the average pre-industrial temperatures of the 1800s. Given that goal, climate science can provide useful information about what actions are needed to give a reasonable chance of meeting the goal. The problem, however, is that the political process has done almost nothing to act, despite the information provided by the science, so the threat of climate change continues to become more and more serious as time goes on. Today the world has already warmed by almost half of the 3.6 degrees Fahrenheit goal, and some further warming is already unavoidable.

We are already watching human-caused climate change occur. It is not only a problem for the future. It is happening here and now. The warming is just a symptom. Climate is complex, and warming has many consequences. Melting Arctic sea ice and rising sea level are consequences. Extreme weather events today occur in a changed environment. For example, Hurricane Sandy, which killed hundreds of people and caused some 75 billion dollars in property damage in 2012, occurred in a climate with higher ocean temperatures and more water vapor in the air than only a few decades ago. The heat-trapping gases and particles that humanity has emitted into the atmosphere increase the odds of severe weather events, just as steroids taken by a baseball player can increase the odds of home runs. Today we are seeing climate change on steroids. To limit global warming to moderate or tolerable amounts, the entire world must act quickly to reduce these emissions. That we have failed miserably to do this already is a great tragedy.

Recent research findings show that previous projections have not exaggerated the threat of climate change. Indeed, in several respects, they may have underestimated it. These findings include measurements showing that the Greenland and Antarctic ice-sheets are losing mass and contributing to sea level rise. Also, Arctic sea-ice extent has decreased far more rapidly than the worst-case expectations of recent climate models.

Carbon dioxide (CO2) is the single most important of the heat-trapping gases that humanity emits into the atmosphere. Current global CO2 emissions from burning fossil fuels are now about 40% higher than those in 1990. Because some of the CO2 that we emit will stay in the atmosphere for many centuries, it is our cumulative emissions that matter. Best current estimates, based on continued “business as usual” emissions scenarios, are that global sea level rise may exceed 1 meter (about 3 feet) by 2100, with a rise of up to 2 meters (about 6 feet) considered possible. If today’s rates of emitting heat-trapping gases continue without change, then after just 20 more years the world will probably no longer be able to limit warming to less than 2 degrees Celsius.

To have a reasonable chance of meeting this 2 degree Celsius goal, the science shows that global emissions of heat-trapping gases must peak soon and then start to decline rapidly, not in 50 or 100 years, but within the next 5 to 10 years, reaching near zero well within this century. Given the politically chosen 2 degree Celsius goal, the case for great urgency in taking meaningful actions to reduce emissions is a consequence of science, thus something based on facts and evidence. It is not an ideological or political choice.

If the world continues to procrastinate throughout the current decade, so that global emissions of heat-trapping gases continue unabated for another ten years, then we will have almost certainly lost the opportunity to limit warming to 2 degrees Celsius. Instead, our children and grandchildren will be forced to cope with more severe climate disruption. The failure of humanity to take meaningful actions now has the effect of condemning future generations to suffer from our ignoring the problem. That would be a great tragedy, but it is the most likely result, unless we change our ways and act soon.

Richard C. J. Somerville
Distinguished Professor Emeritus and Research Professor
Scripps Institution of Oceanography
University of California, San Diego

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by | May 13, 2013 · 11:56 pm

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